Question

我正在使用C和SDL为Conway的生活游戏创建一个模拟。为了表示活细胞，我想在创建的窗口中创建多个矩形。是否可以在不重新定义SDL_Rect的情况下在for循环中调用SDL_Rect并在同一渲染器上全部输出for循环的结果？谢谢。

我的代码：

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <time.h>
#include <stdbool.h>
#include <SDL.h>
#define main SDL_main
#undef main

double CreateRectanglesX()
{   
    double x; double x_max = 640; double x_min = 20;
    x = rand() / (x_max - x_min) / (double)RAND_MAX + x_min;
    return x;
}

double CreateRectanglesY()
{
    double y; double y_max = 480; double y_min = 20; 
    y = rand() / (y_max - y_min) / (double)RAND_MAX + y_min;
    return y; 
}

int main(int argc, char* argv[])
{
    SDL_Init(SDL_INIT_VIDEO); //initializes the SDL/SDL2 window

    SDL_Window *screen; //SDL window created with pointer 
    screen = SDL_CreateWindow("My Program Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 480, SDL_WINDOW_OPENGL); 
    //definition for pointer - dimensions of SDL window

    SDL_Renderer *renderer; //Renderer created with pointer
    renderer = SDL_CreateRenderer(screen, -1, SDL_RENDERER_ACCELERATED); //definition for pointer - still to learn

    if (screen == NULL) //checks if window exists or not
    {
        printf("Could not create window: %s\n", SDL_GetError()); //returns error if window doesn't exsit
        return 1;
    } 

    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); //changes color of renderer
    SDL_RenderClear(renderer); 
    SDL_RenderPresent(renderer); //displays the renderer with the changed color

    for (int i = 0; i < 5; i++)
    {
        double x = CreateRectanglesX();
        double y = CreateRectanglesY();
        printf("%lf %lf", x, y);
        SDL_Rect a;
        a.x = x;
        a.y = y;
        a.w = 20;
        a.h = 20;
        SDL_SetRenderDrawColor(renderer, 0, 0, 255, 255);
        SDL_RenderFillRect(renderer, &a);
        SDL_RenderPresent(renderer);
    }

    SDL_Delay(5000); //wait time for window
    SDL_DestroyWindow(screen);
    SDL_QUIT;

    return EXIT_SUCCESS;
}

Answer 1

错误是事实，我的带有CreateRectanglesX（）和CreateRectanglesY的随机数生成公式是错误的。是

class Index extends React.Component {
  state = {drawerOpened: false}

  handleClick = e => {
    e.preventDefault();
    this.setState(prevState => ({
      drawerOpened: !prevState.drawerOpened
    }))
  };

  render() {
    return <div className={styles.root}>
      <AppBar position="static">
        <Toolbar>
          <IconButton
            className={styles.menuButton}
            color="inherit"
            aria-label="Menu"
            onClick={this.handleClick}
          >
            <MenuIcon/>
          </IconButton>
          <Typography variant="h6" color="inherit" className={styles.grow}>
            Example
          </Typography>
          <Button color="inherit" style={{ right: "0px", position: "absolute" }}>
            Login
          </Button>
        </Toolbar>
      </AppBar>
      <SwipeableDrawer open={this.state.drawerOpened}>
        <div tabIndex={0} role="button">
          {sideList}
        </div>
      </SwipeableDrawer>
    </div>
  }
}

应该是：

v = rand() / (x_max - x_min) / RAND_MAX + x_min;

由于使用随机生成函数生成的随机数太近（由于公式错误），因此仅显示一个矩形。修正公式可以解决问题！

使用SDL_Rect创建多个矩形

1 个答案: